Fuel efficiency is of increasing importance to the operation of land vehicles in light of rising fuel prices and ecological concerns. This is especially true in the field of over-the-road highway trucks. These trucks travel great distances at relatively high speeds. Any improvement that reduces the aerodynamic drag on the truck at highway speeds can have a significant impact on the fuel economy of the truck.
Typically, over-the-highway trucks include a number of body components aimed at reducing drag and improving fuel economy. For example, some trucks have fairings installed above the roof of the cab to direct air more smoothly over the transition between the cab and the trailer. The design of hoods and fenders focuses on creating an aerodynamic surface. Another component that is often used to reduce drag is the air dam, which is a deflective shield installed between the frame of the truck and the ground. An air dam routes air around the truck's bottom smoothly to improve aerodynamic performance.
While devices such as air dams and fairings are useful to route air around portions of the truck to improve fuel efficiency, they form a relatively large “sail” surface that is exposed to the airflow directed toward the truck. This sail surface limits the gain in fuel efficiency that can be realized by such conventional devices.
Accordingly, there is a need in the art for a method and apparatus for minimizing the aerodynamic drag experienced by an over-the-road vehicle while underway. The method and apparatus can optionally minimize the surface area exposed approximately perpendicularly to the airflow, and gradually deflect portions of the airflow directed toward an axle assembly of the vehicle in a plurality of directions around the axle assembly.